When nystagmography became available, a changing pattern of the slow component of nystagmus was recognized. It was observed that the speed of the eye motion may be slower or faster while the slow component is executed. Individual variations exist but there is a changing pattern during the sequence of evoked nystagmus. Measuring the velocity of the slow phase by degree/sec at culmination of the caloric nystagmus became available as a useful parameter of nystagmus intensity. Later, it was proven that in every individual the velocity of the slow phase is proportional to the magnitude of end-organ stimulation. Furthermore, eye speed increases linearly with increased strength of the stimulation. The reliability, therefore, is obvious and the eye speed measurement of the evoked vestibular nystagmus has gained widespread popularity. However, there are numerous problems, shortcomings and pitfalls in measurement of the slow phase speed. The difficulties are enumerated and discussed briefly.